North Korea is highly likely to attack again, South Korea's intelligence chief has told MPs, according to Seoul-based media.

His remarks come a week after an artillery bombardment killed two civilians and two soldiers on Yeonpyeong island – and hours after the South announced fresh military manoeuvres.

Won Sei-hoon, director of the National Intelligence Service, warned: "There is a high possibility that the North will make another attack."

He said the shelling had come amid domestic pressure in Pyongyang, telling a closed session of a parliamentary committee that "internal complaints are growing about the North's succession for a third generation, and its economic situation is worsening".

Won also said a wire tap in August had indicated an attack in the West Sea, according to Yonhap news agency.

Pyongyang said last week's bombardment was a response to the South's live-fire drill.

Yonhap reported that South Korea planned to hold further artillery training exercises next week, including some in an area close to its disputed maritime border with the North. Analysts warned that could increase tensions.

China's foreign minister called for restraint and said all parties should avoid any actions that could "inflame the situation".

"Our general goal is for all sides to exercise calm and restraint and to make every effort to avoid such incidents recurring," Yang Jiechi said.

He said that China, North Korea's main ally, did not seek to "protect any side" and would not "pour oil on the flames", according to the country's official Xinhua news agency.

Yonhap said the military had issued an advisory notice to local vessels for a six-day period from next Monday. Daecheong island – just south of the disputed Yellow Sea border – is included, although Yeonpyeong is not, according to officials from the Korea Hydrographic and Oceanographic Administration.

The news agency cited government sources as saying separate artillery drills would take place in waters off Yeonpyeong soon. Reuters said the defence ministry would not comment.

A South Korean joint chiefs of staff officer said Seoul and Washington were discussing whether to conduct more joint military drills this month or early next month.

Analysts believe the most likely outcome of the current standoff is further negotiations, and that North Korea's actions are in part intended to push Seoul and Washington back towards talks based on giving the North aid in exchange for a pledge on scaling back its nuclear capabilities.

The US has described its participation in this week's manoeuvres as a deterrent, while the South's defence minister warned there was an "ample possibility" of a provocation by the North following the departure of US warships.

But some analysts warned that more military drills could escalate a delicate situation.

"The overall situation might be intensified and a new crisis might be brought by doing this," said Professor Chu Shulong, an expert on international security at Beijing's Tsinghua University.

He added: "Because of the Cheonan incident in March and the shelling in Yeonpyeong, [South Korean] people are angry and their anger has not been addressed yet. They are not happy with the reaction of the government.

"At the same time, South Korea cannot attack North Korea. They can only express their anger through military drills; it is their only way to show the determination to defend their country and to warn the North."

Dr Leonid Petrov, an expert on the North at the University of Sydney, added: "Conservatives in Pyongyang and Seoul are driving the situation to a new extreme."

He added that the "responsible" course for the US would be to talk to the North.

Beijing – under pressure to rein in its ally – threw the ball back into Washington's court by calling for an emergency meeting of the six nations involved in the stalled aid-for-denuclearisation talks.

But the US, South Korea and Japan have snubbed that proposal, instead planning to hold trilateral talks next week.

Japan sent its envoy to the nuclear talks to China today. The senior North Korean leader Choe Thae Bok is currently in Beijing and China's state councillor Dai Bingguo is expected to travel to Pyongyang shortly.

A Russian nuclear envoy, Grigory Logvinov, will meet officials in Seoul to discuss the attack, the six-party talks and other issues, said South Korea's foreign ministry.